Abstract:

Abstract: Based on the small model seat of firefighting water monitor that has inner diameter of 66 mm and large rotary structure, a new- style flow passage with elliptical cross- section is proposed. The numerical simulation method is used to compare and study the difference caused by the change of cross- section, and the particle image test technology (PIV) is used to verify the numerical simulation results. The conclusion of the comparative study is as follows: After part of the circular cross- section flow passage is flattened vertically into ellipse, the whole hydraulic loss increased a little, and the variation of turbulent kinetic energy at the outlet is small. At the outlet, the streamline pattern changed,the calculating eddy flux decreased and the velocity deviation decreased. For the radial velocity distribution curve, the peak value reduced and the low value increased. These evidences show that the flow uniformity is improved. When compared the simulation results with the PIV experiment data, the axial velocity deviation is less than 2.3%, the radial velocity deviation is about 8%, and the value of turbulent kinetic energy have the same order of magnitude. PIV test results are consistent with the numerical simulation results in velocity distribution, but it is necessary to improve the test accuracy in distinguishing the difference between two kinds of flow passage.

Key words:  , fire-fighting water monitor, seat, elbow, PIV experiment, uniformity of velocity ,  ,